As President Obama spoke on Tuesday about acting against gun violence, Jim Fox was on the phone, trying to make sure that every one of the 3,000 or so players in his basketball league, Lightning Basketball, would have a jersey with an orange patch.

The patch signifies that those young men and women, boys and girls, are part of the Wear Orange campaign to end the showers of bullets that maim and kill young people like themselves.

“I’m just fighting with the uniform guy,” said Mr. Fox, who is also a governor of the Amateur Athletic Union for the New York region. He said that at A.A.U. games, referees and other officials would wear orange shirts.

This is a small, spreading prairie fire. It began with 200 young ballplayers in another program, the New Renaissance Basketball Association, known around New York as the Rens. They started wearing the orange patches in October, after two players were badly hurt by gunfire and two others were accused of having fired guns within 18 months.

No president or senators are involved; no legislation is tied in knots. So far, about 300 amateur teams across the country have joined the Rens. In New Jersey, Connecticut, Maryland and Florida, league leaders have promised that their teams will be wearing the patch.

Patches have gone to Team CP3, three teams in North Carolina sponsored by Chris Paul, the star point guard for the Los Angeles Clippers and president of the N.B.A. players’ union. “My @TeamCP3YB will be backing this initiative,” Mr. Paul wrote on Twitter after reading a column on the Rens’ orange patches.

Carmelo Anthony, the Knicks small forward, who underwrites Team Melo Basketball in Baltimore, also declared his support on Twitter.

No one believes that an orange patch can stop gun violence. The idea, said Andy Borman, the executive director of the Rens, is to disrupt the ordinariness of gunfire, the shrugging, undeclared normality of it among young men and boys.

To date, the orange project has been passed along from one amateur group to another, without the involvement of the National Collegiate Athletic Association or in New York, of the Public Schools Athletic League or the Catholic High School Athletic Association.

“The next step is helping to create an environment in which the N.C.A.A. is comfortable enough to act, so college presidents are behind the orange emblem,” Mr. Borman said. “For the mayor to feel comfortable enough so that all P.S.A.L. teams wear it, and for the cardinal to ask all C.H.S.A.A. teams to wear it. Being against gun violence is being for humanity.”

Mr. Fox, who retired as the chief federal probation and parole officer for New York, said that about 100 coaches in his league met on Sunday in an American Legion hall on Long Island and that there was immediate, broad enthusiasm for the plan. One of the league’s 16-year-old players was killed three years ago in a shooting, Mr. Fox said, and another lost part of his leg.

“We’re not talking about politics or Second Amendment stuff,” Mr. Fox said. “Kids are being hurt by guns that are almost always illegal.”

In his speech, Mr. Obama invoked the mass-shooting deaths that have stained this era in American history; the memory of the first graders slaughtered in Newtown, Conn., three years ago ran in tears across his face as he spoke.

“Every time I think about those kids it gets me mad,” Mr. Obama said. “And by the way, it happens on the streets of Chicago every day.”

That reality had already prompted Daniel Ferreira, coach of the Skyhawks in the Chicago Park District, to order T-shirts with the orange insignia for players on his teams.

“The majority of my guys are former gang members,” Mr. Ferreira said. “The Rens story struck a chord with me, because it’s the teams that identify strongly as families that are the ones that do well. About 85 percent of the players on our teams are survivors of gun violence. It’s an unfortunate reality here in Chicago.”

Indeed, it was injuries from those shootings that brought those players to the Skyhawks. When the season gets going, everyone on the court will be wearing a shirt with an orange patch. It will be a second reminder about the perils of bullets: the Skyhawks are part of a wheelchair basketball league.